Question

Which of the following functions represents a repairman's fee if he charges a $25 service call fee plus $15 for each hour he works? f(h) = 25h + 15 f(h) = 15h + 25 f(h) = 40h

Answer 1

Sample Response: 15h + 25 is correct because there is one $25 fee, and there is a fee of $15 for each hour, or “h.” The constant is 25, and the variable is h. The second expression adds hours and dollars, which is not correct.

Answer 2

Thinking about y = mx + b or f(x) = mx + b where m is the slope (rate of change) and b is the y-intercept (fixed fee or initial cost) you would get the following equation:
$25 fixed service call fee = b
$15 for each hour = m

ANSWER ⇒ f(h) = 15h + 25